Studies on the Sugar Metabolism in the Germinating Stage of the Lowland Rice Seeds.

Abstract

Paper-chromatographic analysis was done on the sugar contained in embryo and endosperm of the lowland rice seed, and of each of the youngest seedling and its endosperm, i. e., Norin No. 41 (translucent grain) which requires more oxygen for germination and Hikotaro-mochi(non-translucent grain) which requires less, both being germinated at 30°C on the water blotted paper, in water 5 cm depth, and in water 5 cm depth and vacuumed by rotary pump. Sugars detected in this experiment were raffinose, sucrose, glucose, fructose and two unidentified sugar-like substances. Raffinose was disappeared as germination progressed, but galactose to be produced by its hydrolysis was not found. Sucrose was always detected in seeds regardless of the different germinating conditions. It was considered that hexoses were synthesized into sucrose as a precusor-like type or a translocating type. Maltose which should be naturally produced from starch was not fund. It may be produced from starch by amylase in vivo, without regards the weak intensity of its reaction, because pH values of cell saps in the embryo and the endosperm of two kinds of seeds are greater than optimum value in vitro. Hexose were found in each of two kinds of seeds at 4-8 hours after the imbedding on the water blotted paper or by submerging in the water of 5 cm depth, but these were found only in the endosperm during 4-20 hours in the anaerobic condition while in embryo and endosperm it takes 24 hours. From above results, as disclosed dy DASTUR and DESAI (1935), enzymic activities in the germination were pormoted by a successive supply of oxygen, while these were inhibited under the anaerobic condition, particularly invertase was concerned. In this connection, it is considered that hydrolysis of sucrose by invertase is the most important factor for the germination and the suceeding growth of the seedling.